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Multi-Select ListView

I was just hanging around in the IDE this week and I had a chat with ListView. He was a very nice guy, but he was complaining about the fact that for some reason he could only ever select one item at a time…

I think of myself as a somewhat decent coder, and I decided to solve this problem – at least some part of it.

The easiest, and quickest, way to add multi-select capabilities to a ListView requires two steps: the “selectable” item and the “select” action.

You may have noticed that I didn’t create a generic type. This is because later on we are going to want to get the value of the IsSelected property from the ItemSelected event handler, and we won’t know what the type is. However, we can create a generic type that inherits from this base type:

This is all we need, and we will have a ListView that that can support multiple items being selected.

Improvements

We could call it a day, but we are not going to. The day has just started, and we are thinking that we might want to use this in multiple places. We can just copy the logic – mainly the event and cell view, but there are better ways (and we don’t like duplicate code).

Attached Property

The first thing that we will look at is if we can magically do the event hookup with a single property instead of the event:

We now have a super easy way to turn any list into a multi-select list with a single property.

The ItemsSource

Another area we can improve is the ItemsSource collection. Right now we have quite a long type with two generic types:

public ObservableCollection<SelectableItem<string>> Items { get; }

We can not only make this shorter, but more convenient by creating a new type that derives from ObservableCollection. And, now that we have a new type, we can add additional methods so that we don’t even have to deal with the SelectableItem type at all:

The Cell

Finally, as you may have a really cool check mark for selected items (unlike our red block now), we will want to be able to create a custom cell type that will allow us to just specify the item contents, and automatically handle the check mark:

Hi, I have implemented, But I found that If I remove selected Items items are removing properly from list , But when trying to select remaining items, some items are not getting selected. could you please let me know have you ever faced an issue and fix for this. Thank you